Balance Sheet Components Pension and Other Postretirement Benefits (Details) - Pension Plan [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 4	$ 5
Interest cost	8	8
Expected return on plan assets	(10)	(10)
Amortization of net actuarial loss	3	4
Net periodic benefit cost	$ 5	$ 7